[en] Reasons for performing study: Inflammatory airway disease (IAD) is a nonseptic condition of the lower respiratory tract. Its negative impact on respiratory function has previously
<br /><br />been described using either forced expiration or forced oscillations techniques. However, sedation or drug-induced bronchoconstriction were usually required. The impulse
<br /><br />oscillometry system (IOS) is a noninvasive and sensitive respiratory function test validated in horses, which could be useful to evaluate IAD-affected horses without further
<br /><br />procedures.
<br /><br />Objectives: To determine the sensitivity of IOS in detecting alterations of the respiratory function in subclinically IAD-affected horses without inducing bronchoprovocation and to characterise their respiratory impedance according to frequency for each respiratory phase.
<br /><br />Methods: Pulmonary function was evaluated at rest by IOS in 34 Standardbred trotters. According to the cytology of bronchoalveolar lavage fluid (BALF), 19 horses were defined
<br /><br />as IAD-affected and 15 horses were used as control (CTL). Total respiratory resistance (Rrs) and reactance (Xrs) from 1–20 Hz as well as their inspiratory and expiratory
<br /><br />components were compared between groups.
<br /><br />Results: A significant increase of Rrs at the lower frequencies (R1–10 Hz) as well as a significant decrease of Xrs beyond 5 Hz (X5–20 Hz) was observed in IAD compared to CTL horses. IOS-data was also significantly different between inspiration and expiration in IAD-affected horses. In the whole population, both BALF eosinophil and mast cell counts were
<br /><br />significantly correlated with IOS measurements.
<br /><br />Conclusions: Functional respiratory impairment may be measured, even in the absence of clinical signs of disease. In IAD-affected horses, the different parameters of respiratory
<br /><br />function (Rrs or Xrs) may vary depending on the inflammatory cell profiles represented in BALF.
<br /><br />Potential relevance: Impulse oscillometry could be used in a routine clinical setting as a noninvasive method for early detection of subclinical respiratory disease and of the results
<br /><br />of treatment in horses.